Externally threaded expandable orthopedic implant

ABSTRACT

An expandable screw for orthopedic insertion and expansion between a collapsed state and an expanded state. The screw has an upper externally-threaded body segment, a lower externally-threaded body segment opposite the upper external thread segments, and an expansion member extending along a longitudinal axis thereof. The expansion member connecting the upper externally-threaded body segment to the lower externally-threaded body segment, and configured during the expansion between the collapsed state and the expanded state to separate the upper externally-threaded body segment from the lower externally-threaded body segment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority to U.S. Ser. No.17/496,081 entitled EXTERNALLY THREADED EXPANDABLE ORTHOPEDIC IMPLANTfiled Oct. 7, 2021 (the entire contents of which are incorporated hereinby reference), This application is related to U.S. Pat. No. 10,278,830,entitled Expandable Orthopedic Implant, filed Sep. 19, 2018, the entirecontents of which are incorporated herein by reference. This applicationis related to U.S. Ser. No. 17/235,587, entitled Improved-ExpandingOrthopedic Implant, filed Sep. 19, 2021, the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to implant devices for treating inparticular spinal disorders.

Description of the Related Art

Disorders of the bone include disorders such as for example degenerativedisc disease, disc herniation, osteoporosis, spondylolisthesis,stenosis, scoliosis (and other curvature abnormalities), kyphosis,tumor, fracture, arthritis, calcification, etc. Such disorders mayresult from factors including trauma, disease and degenerativeconditions caused by injury and aging. Bone disorders typically resultin symptoms including pain, nerve damage, and partial or complete lossof mobility. Additionally, severe pain and discomfort can occur due tothe pressure exerted by bones on nerves.

In the field of medical implant devices, implant devices are often usedin a collapsed state and expanded to a desired height. The followingprovides a non-exhaustive list of expansion devices known in the art.

U.S. Pat. No. 6,500,205 (the entire contents of which are incorporatedherein by reference) describes a threaded implant having arcuateportions of upper and lower members that in a first, collapsed, orinsertion position are parallel to one another and form at least aportion of a cylinder along a substantial portion of the length of theimplant.

U.S. Pat. No. 7,128,760 (the entire contents of which are incorporatedherein by reference) describes interbody spinal fusion implants being atleast in part radially expandable at one of the leading or trailing endsto expand both the height and at least a portion of the width of theimplants.

U.S. Pat. No. 7,655,046 (the entire contents of which are incorporatedherein by reference) describes an expandable spinal implant comprising acage body including at least two movable branches having first endportions that are interconnected to one another and second end portionsthat are movable relative to one another. An expansion member in the'046 patent co-acts with first and second shell portions to transitionthe cage body to an expanded configuration as the expansion member isaxially displaced along said first and second pairs of longitudinaledges.

U.S. Pat. No. 8,241,360 (the entire contents of which are incorporatedherein by reference) describes an artificial disc device for replacing adamaged nucleus in which the device may be inserted into the naturalannulus in a collapsed or compressed state or arrangement and then maybe expanded within and retained by the annulus therein.

U.S. Pat. No. 8,535,380 (the entire contents of which are incorporatedherein by reference) describes an implantable orthopedic stabilitydevice. The device had a contracted and an expanded configuration whichcould support and be fixed to either or both of adjacent vertebrae.

U.S. Pat. No. 8,894,712 (the entire contents of which are incorporatedherein by reference) describes an expandable intervertebral implant,including: a superior member configured to engage a superiorintervertebral body; an inferior member configured to engage an inferiorintervertebral body; and an expansion mechanism disposed between thesuperior member and the inferior member configured to selectively adjusta separation of the superior member from the inferior member.

U.S. Pat. No. 8,679,183 (the entire contents of which are incorporatedherein by reference) describes an expandable fusion device capable ofbeing installed inside an intervertebral disc space to maintain normaldisc spacing and restore spinal stability.

U.S. Pat. No. 9,320,610 (the entire contents of which are incorporatedherein by reference) describes an expandable implant including top andbottom plates having angled inner surface that interact with expansionmembers. The expansion members of the '610 patent were situated on anactuator and included at least one vertical projection for interactingwith a recess in the plates.

U.S. Pat. No. 9,414,936 (the entire contents of which are incorporatedherein by reference) describes an intervertebral implant comprising afirst component and a second component. The second component included anactuator and a third component comprises a first ramp and a second rampaxially spaced apart from the first ramp. The third component comprisedrails including at least a portion of the ramps. The actuator wasengageable with the third component to effect axial translation suchthat the ramps engage at least one of the components between a firstconfiguration and a second configuration.

U.S. Pat. No. 9,526,627 (the entire contents of which are incorporatedherein by reference) describes an intervertebral implant to be implantedwithin an intervertebral space between endplates of adjacent vertebraduring use.

U.S. Pat. No. 9,717,601 (the entire contents of which are incorporatedherein by reference) describes an implant including a first plate and asecond plate, a first wedge member and a second wedge member spaced fromthe first wedge member that couple the first and second plates together.

U.S. Pat. No. 9,717,605 (the entire contents of which are incorporatedherein by reference) describes a spinal fusion device that isexpandable. The spinal fusion device of the '605 patent features a topand bottom surface for engaging adjacent vertebrae, a hollow center forstacking of bone or bone growth material, and a slidable mechanism withgrooves for expanding or un-expanding the device.

U.S. Pat. No. 9,770,343 (the entire contents of which are incorporatedherein by reference) describes a spacer for separating bones of a joint,the spacer includes a frame having a longitudinal axis, and rampedsurfaces. In the '343 patent, an endplate configured to engage a bone ofthe joint had ramped surfaces mateable with the ramped surfaces of theframe. When the endplate was moved relative to the frame in a directionalong the longitudinal axis of the frame, the endplate was moved in adirection away from the frame to increase the height of the spacer.

U.S. Pat. No. 9,788,971 (the entire contents of which are incorporatedherein by reference) describes an expandable spinal fusion implantcomprising first and second endplates coupled to an expansion memberthat sits within a housing.

U.S. Pat. No. 10,350,081 (the entire contents of which are incorporatedherein by reference) describes an orthopedic device for a patientcomprising: a spacer comprising: a body member; a translation memberreceived in the body member, the translation member including at leastone upper ramp portion and one lower ramp portion; an upper endplatehaving an upper contact surface for engaging a first vertebra and atleast one lower ramp for engaging the upper ramp portion of thetranslation member, wherein the upper endplate includes an upper plateportion comprising a bottom post; a lower endplate having a lowercontact surface for engaging a second vertebra and at least one upperramp for engaging the lower ramp portion of the translation member.

U.S. Pat. No. 10,383,741 (the entire contents of which are incorporatedherein by reference) describes an expandable implant including a topsupport assembly defining an upper surface configured to engage a firstportion of vertebral bone; a bottom support assembly defining a lowersurface configured to engage a second portion of vertebral bone; and acontrol assembly coupled to the top support assembly and the bottomsupport assembly and configured to control relative movement between thetop support assembly and the bottom support assembly between a collapsedposition and an expanded position.

U.S. Pat. No. 10,492,924 (the entire contents of which are incorporatedherein by reference) describes an expandable spinal fusion implantincluding a housing, upper and lower endplates, a wedge positionedwithin the housing and between the upper and lower endplates and a drivemechanism to urge the wedge distally between the upper and lowerendplates to increase the separation between the endplates and expandthe overall height of the distal end of the implant.

U.S. Pat. No. 2020/0297507 (the entire contents of which areincorporated herein by reference) describes a joint spacer fortherapeutically maintaining a separation of bones of a joint. The jointspacer comprises a frame having distal and proximal ends defining alongitudinal axis extending therebetween, a carriage slideably retainedwithin the frame, an actuator screw threadably engaged with the frame,whereby when the carriage is slideably moveable by rotation of theactuator screw, an endplate ramped surface slides against a carriageramped surface to cause the endplate to move along an axis transverse tothe longitudinal axis to increase a height of the spacer.

SUMMARY OF THE INVENTION

In one embodiment, there is provided an expandable screw for orthopedicinsertion and expansion between a collapsed state and an expanded state.The screw has an upper externally-threaded body segment, a lowerexternally-threaded body segment opposite the upper external threadsegments, and an expansion member extending along a longitudinal axisthereof. The expansion member connecting the upper externally-threadedbody segment to the lower externally-threaded body segment, andconfigured during the expansion between the collapsed state and theexpanded state to separate the upper externally-threaded body segmentfrom the lower externally-threaded body segment.

In one embodiment, there is provided a system for orthopedic insertionand expansion of an expandable screw into a bone segment of a patient,the system comprising an expandable screw, and an insertion tool whichis configured to connect to the screw for actuation and expansion of thescrew.

In one embodiment, there is provided a method for orthopedic insertionand expansion of an expandable screw into a bone segment of a patient,comprising inserting an expandable screw into the bone segment; andexpanding the expandable screw.

It is to be understood that both the foregoing general description ofthe invention and the following detailed description are exemplary, butare not restrictive of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawing, wherein:

FIG. 1 is a side view of an expandable screw in a collapsed state and inan expanded state;

FIG. 2 is an end view of the expandable screw of FIG. 1 ;

FIG. 3 is a perspective view of the of the expandable screw in thecollapsed state and in the expanded state;

FIG. 4 is a perspective view of a threaded segment of the expandablescrew of FIG. 1 ;

FIG. 5 is a schematic depiction of the individual components of theexpandable screw, showing the relative positions of those components;

FIG. 5 is a schematic depiction of the individual components of theexpandable screw with attention on the dovetail groove assemblyconstruction;

FIG. 6 is a schematic depicting an expanded view of a pin and actuatorconfiguration for the expandable screw of FIG. 1 ;

FIG. 7 is a schematic depicting a dovetail configuration for theexpandable screw of FIG. 1 ;

FIG. 8A is a schematic depicting counter torque slots of the expandablescrew;

FIG. 8B is an alternative to the configuration of FIG. 8A; and

FIG. 9 is a flowchart depicting a method of the invention for orthopedicinsertion and expansion of an expandable screw into a bone segment of apatient.

DETAILED DESCRIPTION OF THE INVENTION Expandable Screw Devices of theInvention

In one embodiment of the invention, as noted above, there is provided anexpandable screw 10 for orthopedic insertion and expansion into a bonesegment of a patient, although this invention is not limited to thisspecific target use.

With reference to FIG. 1 , FIG. 1 is a perspective view of theexpandable screw 10 in a collapsed state and in an expanded state. Inone embodiment of the invention and as shown in FIG. 1 , expandablescrew 10 has an upper externally-threaded body segment 12, a lowerexternally-threaded body segment 14 opposite the upper external threadsegments 12, and an expansion member 16 extending along a longitudinalaxis thereof. Expansion member 16 connects the upper externally-threadedbody segment 12 to the lower externally-threaded body segment 14.(Details of connecting expansion member 16 to the upperexternally-threaded body segment 12 to the lower externally-threadedbody segment 14 and to nose member 20 are provided below.) Expansionmember 16 is configured (during the expansion between the collapsedstate and the expanded state) to separate the upper externally-threadedbody segment 12 from the lower externally-threaded body segment 14. Inone embodiment, in the collapsed state, the threads on the nose memberand the threads on the expansion members match-up or align with eachother. In one embodiment, the threads on the nose member and the threadson the expansion members have the same pitch. When the expandable screwis made, the ends of the threads on the expansion members are formed(made to start) at the point where the thread on the nose member wouldend. That is the starting point for the thread machining on eachcomponent is defined/controlled relative to a common datum, such thatthe component threads will be aligned and form a uniform screw threadwhen assembled.

FIG. 2 is an end view of the expandable screw 10 showing the collapsedstate and the expanded state. FIG. 2 shows expansion member 16 expandingthe upper externally-threaded body segment 12 from the lowerexternally-threaded body segment 14 in a single expansion direction A.Accordingly, in one embodiment, screw 10 expands in a substantiallysingle direction of motion, the deviations therefrom depending on themechanical tolerances of the expansion member and its mechanicalconnections to the upper externally-threaded body segment 12 from thelower externally-threaded body segment 14. As used herein, “in a singleexpansion direction” means movement in one direction with only minordeviations from the expansion directions due to mechanical tolerances ofthe expansion member and its mechanical connections to the upperexternally-threaded body segment 12 from the lower externally-threadedbody segment 14.

Additionally, in one embodiment. the expansion member 16 can expand theupper externally-threaded body segment 12 from the lowerexternally-threaded body segment 14 in a single expansion directionwithout a radial deflection of the upper externally-threaded bodysegment 12 from the lower externally-threaded body segment 14.Accordingly, in one embodiment, screw 10 expands without a radialdeflection of the upper externally-threaded body segment 12 from thelower externally-threaded body segment 14. Similar to that noted above,as used herein, “without radial deflection” means that, upon movementbetween the collapsed state and the expanded state, there are only minorradial deflection due to mechanical tolerances of the expansion memberand its mechanical connections to the upper externally-threaded bodysegment 12 from the lower externally-threaded body segment 14.

In another embodiment, the expansion member 16 can expand the upperexternally-threaded body segment 12 from the lower externally-threadedbody segment 14 while the upper externally-threaded body segment 12 andthe lower externally-threaded body segment 14 remain in a substantiallyfixed orientation relative to each other. Similar to that noted above,as used herein, “remains in a substantially fixed orientation” meansthat, upon movement between the collapsed state and the expanded state,there are only minor deviations from the relative orientation of theupper externally-threaded body segment 12 to the lowerexternally-threaded body segment 14 due to mechanical tolerances of theexpansion member and its mechanical connections to the upperexternally-threaded body segment 12 from the lower externally-threadedbody segment 14.

As seen in FIG. 1 , the upper externally-threaded body segment 12 andthe lower externally-threaded body segment 14 in one embodiment caninclude threads 12 a, 14 a. Threads 12 a and 14 a are for securing theexpandable screw 10 to a bone segment of a patient. Thread 12 a on theupper externally-threaded body segment 12 is disposed on the upperexternally-threaded body segment 12 in a manner that thread 12 a alignswith (or matches) thread 14 a on the lower externally-threaded bodysegment 12 when the expandable screw 10 is in the collapsed state.

As seen in FIG. 4 , upper externally-threaded body segment 12 cancomprise an elongated body 22 having an aperture 24 which can extend inlongitudinal and transverse directions of the elongated body 22. Theaperture may be used for graft filling. Further, as seen in FIG. 4 , thethreads 12 a, 14 a can be disposed on outer peripheral sections 22 a ofelongated body 22. This thread arrangement is likewise applicable to thelower externally-threaded body segment 14. As also seen in FIG. 4 ,upper externally-threaded body segment 12 can comprise a cylindricalshell or be formed in a cylindrical shape. This shell configuration islikewise applicable to the lower externally-threaded body segment 14.

The Expansion Member

Expansion Member 16 in one embodiment can include a wedge member 18connecting the upper externally-threaded body segment 12 to the lowerexternally-threaded body segment 14, a nose member 20 having a distalend and a proximal end opposite the distal end, the nose member 20slidably connected to the upper externally-threaded body segment 12 andthe lower externally-threaded body segment 14, and an actuator 33disposed between the nose member 20 and the wedge member 18, fortranslation of the wedge member 18 along a longitudinal axis of thescrew.

FIG. 5 is a schematic depiction of the individual components of theexpandable screw 10 (including specific components of expansion member16) showing the relative positions of those components. As evident fromFIG. 5 , actuator 33 is disposed between nose member 20 and wedge member18. In one embodiment of the invention, the wedge member 18 comprises afirst wedge 18 a and a second wedge 18 b connected together by one ormore rails 18 c. With reference to FIG. 5 , nose member 20 connects topin 32. Pin 32 retains the head of actuator 33 during expansion of screw10 and positions the nose member 20 relative to the actuator 33.

In one embodiment, screw 10 expands by utilizing actuator 33 which isconnected by a threaded connection to wedge member 18, which containsfor example a pair of wedges 18 a, 18 b. When rotated, actuator 33 pullsthe wedges (as a set) closer to the nose member 20 of and, in turn,drives the upper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 away from each other and away fromthe centerline of screw 10. In other words, with actuator 33 beingthreadably connected to wedge member 18, rotating actuator 33 translatesthe wedge member 18 along the longitudinal axis of screw 10. Actuator 33in one embodiment has a threaded outside surface 33 a with a head 33 bof the actuator, opposite the wedge member 18, closer to the nose member20 than to the posterior of screw 10. In one embodiment, actuator 33 andwedge member 18 have respectively male and female threads to therebyadvance wedge member 18 when the actuator 33 is turned.

In one embodiment, actuator 33 is connected (e.g., by dovetail andgroove construction) one side to nose member 20 and is connected (e.g.,by dovetail and groove construction) on another side to wedge member 18.Translation of the wedge member 18 (for example along the longitudinalaxis) in one embodiment displaces the upper externally-threaded bodysegment 12 from the lower externally-threaded body segment 14, andthereby expands the upper externally-threaded body segment 12 away fromthe lower externally-threaded body segment 14. Actuator can threadablyconnected to the wedge member such that rotating the actuator 33translates the wedge member 18 along the longitudinal axis.

In one embodiment of the invention, actuator 33 is disposed closer tothe nose member 20 than to a posterior of the screw 10. In general, theinventive screw expands by utilizing actuator 33 which is connected by athreaded connection to wedge member 18, which contains for example apair of wedges 18 a, 18 b. When rotated, actuator 33 pulls the wedges(as a set) closer to the nose member 20 of screw 10 and, in turn, drivesthe upper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 away from the centerline of screw10. In other words, with actuator 33 being threadably connected to wedgemember 18, rotating actuator 33 translates the wedge member 18 along thelongitudinal axis of screw 10. Actuator 33 in one embodiment has athreaded outside surface 33 a with a head 33 b of the actuator, oppositethe wedge member 18, closer to the nose member 20 than to the posteriorof screw 10. In one embodiment, actuator 33 and wedge member 18 haverespectively male and female threads to thereby advance wedge member 18when the actuator 33 is turned.

FIG. 6 is an expanded view of the head 33 b of the actuator 33 having aflange 33 c which retains washer 33 d into recess 33 e. Washer 33 d canbe made from similar or dissimilar materials as the actuator, and in oneexample, washer 33 d is made from polyetheretherketone (PEEK). Washer 33d is merely one example of a frictional bearing that provides africtional force retarding movement of the upper externally-threadedbody segment 12 and the lower externally-threaded body segment 14. Asshown in FIG. 6 , pin 32 fits into a reception hole 33 f disposed on acentral axis of the actuator 33. While the circular and symmetricgeometry shown in FIG. 6 is preferred, the washer and its recess neednot be circular and split washers and spacers could be placed on theflange in asymmetric patterns.

Regardless of the material that washer 33 d is made of, washer 33 dserves multiple purposes in the present invention. In one embodiment,compression of washer 33 d in the interface between nose member 20 andactuator 33 provides friction. This friction helps keep the partscentered and prevents binding of the components duringexpansion/contraction. The friction also provides additional resistanceto post operation collapse of the cage.

During assembly, pin 32 is pressed into the nose member 20 with aportion of pin 32 extending beyond the distal end of nose member 20. Theupper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 are coupled to wedge member 18 alongrespective dovetails and dovetail groove with full engagement into acollapsed or non-expanded state. Actuator 33 is threaded into the wedgemember 18. The head position of actuator 33 is adjusted so that it isaligned with the mating slot in nose member 20, while the verticaldovetails of the endplates are aligned with their mating dovetailgrooves in nose member 20. Next, washer 33 d is placed in recess 33 e onflange 33 c of the actuator. Then, the head of actuator 33 (with washer33 d in place) is slid into groove 20 c of nose member 20, compressingwasher 33 d in the process to provide the friction noted above. Once thenose member 20 is close to alignment, pin 32 is pushed through anopening in the washer 33 d into reception hole 33 f of actuator 33. Thepart of pin 32 which formerly was protruding from the distal tip of nosemember 20 is now flush with the distal tip of nose member 20.

In one embodiment of the invention (as described in U.S. Ser. No.17/235,587), the frictional bearing can be a wave spring applying anaxial force on the head of the actuator. In another embodiment of theinvention, the frictional bearing can be a spring loaded cap to apply anaxial force on the head of the actuator. In still another embodiment,the frictional bearing can be a PEEK pellet (or pin) inserted in thenose piece and oriented to interfere with the head of the actuator, andthereby apply an axial force on the head of the actuator.

FIG. 7 is a schematic depiction of the individual components of theexpandable screw 10 with attention on the dovetail groove assemblyconstruction. As seen in FIG. 7 , nose member 20 uses dovetail grooves26 to slidably connect and guide expansion of the body segments 12, 14to wedge member 18, and restrain any anterior-posterior movement of theupper externally-threaded body segment 12 relative to the lowerexternally-threaded body segment 14. Moreover, in one embodiment,dovetail grooves 26 on the wedge member 18 hold and slidably connect thebody segments 12, 14 to the wedge member 18. In another embodiment,dovetail grooves hold and slidably connect the upper externally-threadedbody segment 12 and the lower externally-threaded body segment 14 to thenose member 20.

In still another embodiment, a series of dovetail grooves 26 connectindividual components such as the nose member 20, the body segment 12,the wedge member 18 and the body segment 14 to each other so as to holdthese components together as an expandable assembly. For example, a setof dovetail grooves on the first wedge 18 a and the second wedge 18 bslidably connect the wedge member 18 to the body segment 12 and bodysegment 14.

Additionally, a first set of dovetail grooves 26 on the nose member 20fix the nose member 20 to the upper externally-threaded body segment 12and the lower externally-threaded body segment 14, while a second set ofdovetail grooves 26 on the wedge member 18 fixes the upperexternally-threaded body segment 12 and the lower externally-threadedbody segment 14 to the wedge member 18.

FIG. 8A is a schematic depicting counter torque slots 28 of screw 10 andan opening 30 in the posterior end of expandable screw 10. In oneembodiment, opening 30 comprises a through hole in the posterior wedgemember that opens into aperture 24. The counter torque slots 28 permitan entirety of expandable screw 10 to be rotated. The counter torqueslots 28 may also hold against rotation when the actuation 33 is beingturned. For example, the counter torque slots 28 can stabilizeexpandable screw 10 against the torque being applied by actuator 33during expansion. The opening 30 grants access for the driver to theactuator. The opening 30 also represents a hole for insertion of bonegraft material. In another embodiment of the invention, a through-holein an end of wedge member 18, and a spacing between the rails 18 ccomprise a passageway for an insertion tool to connect to and turnactuator 33, and a passageway for bone graft material insertion. In oneembodiment, the inclusion of aperture 24 and opening 30 in expandablescrew 10 permits the bone graft material to be inserted through eitheror both of these passageways and contact the bone adjacent to bodysegments 12 and 14 and thereby promote bone growth inside the expandablescrew 10.

FIG. 8B is an alternative to the configuration of FIG. 8A in which inFIG. 8B a twelve-point or “double hex” interface 28 a is used. Thedouble hex interface 28 a offers a more robust option for advancing theentirety of the implant into bone as well as providing the countertorque for expansion.

In one embodiment of the invention, there is provided a system fororthopedic insertion and expansion of an expandable screw into a bonesegment of a patient. This system can utilize a) any of the expandablescrews described above; and b) an insertion tool which turns an actuator(as described above) and thereby expands the screw. For example,actuator 33 described above can be rotated by a T-7 hexalobular driveror actuator 33 can be rotated by a hexagonal socket driver. This systemfor orthopedic insertion and expansion of expandable screw 10 canutilize a bone graft inserter, which may be cannulated. In oneembodiment, the above-noted T-7 driver or the hexagonal socket driver isplaced through the center of the bone graft inserter and engages theactuator. Bone graft material is then pushed through the inserter afterscrew 10 has been expanded.

The expandable screws of the present invention are not limited to thetype of material that the screw is made of. The screws of this inventioncan be made of any material appropriate for human implantation andhaving the mechanical properties sufficient to be utilized for theintended purpose of spinal fusion, including various metals such ascobalt chrome, stainless steel or titanium including its alloys, variousplastics including those which are bio-absorbable, and various ceramicsor combination sufficient for the intended purpose. Further, the screwsof this invention may be made of a solid material, a mesh-like material,a porous material and may comprise, wholly or in part, materials capableof directly participating in the spinal fusion process, or be loadedwith, composed of, treated of coated with chemical substances such asbone, morphogenic proteins, hydroxyapatite in any of its forms, andosteogenic proteins, to make them bioactive for the purpose ofstimulating spinal fusion. The screws of this invention may be wholly orin part bioabsorbable. Other materials for the expandable screw besidesthose specifically listed above can be used. In one embodiment, thematerials of the expandable screw can be sterilized either at the timeof manufacturing and/or at the time of insertion into a patient. In oneembodiment, the surface finish of the expandable screw permit chemicalsor steam sterilizing agents to penetrate the components of the screw andsterilize biological material on the surfaces.

This invention is also not limited to the methods by which the screwsare made. The individual components can be machined from solid stockpieces. Molding can be used to make the individual components. In thiscase, machining to final dimensions may or may not be in order. Thesurfaces once properly dimensioned can be coated with a variety ofbiocompatible coatings and/or surface treatments. Various coatingsinclude for example calcium phosphate ceramics, such as tricalciumphosphate (TCP) and hydroxyapatite (HA), and hydroxyapatite (a naturallyoccurring material in bone). Moreover, screw 10 may be treated topromote fusion of the screw to the bone. Treatment may include, but isnot limited to, applying a hydroxyapatite coating on contact surfaces,spraying a titanium plasma on contact surfaces, and/or texturing thecontact surfaces by scoring, peening, implanting particles in thesurfaces, or otherwise roughening the surfaces of the screw.

Operation of Expandable Screw

In one embodiment of the invention, there is provided a method fororthopedic insertion and expansion of an expandable screw into a bonesegment of a patient. FIG. 9 is a flowchart depicting this method. Thismethod at 1001 attaches an insertion tool to any of the expandablescrews described above. At 1003, the method inserts one (or more) of theexpandable screws into to a bone segment of a patient; and at 1005expands the expandable screw.

After the expandable screw has been expanded, at 1007, the insertiontool may be removed (e.g., may be pulled from through hole 30 in theposterior end of screw 20. At 1009, bone graft material may then beinserted into the expanded screw filling the graft in the expanded screwin situ. Insertion of bone graft material may promote increased fusion.

This invention is not limited to a specific type of bone graft material.In general, a variety of bone graft materials are known and suitable forthis invention. These typically comprise calcium phosphate-based orgel-based materials. Polymer-based bone graft substitutes containing (ornot containing) collagen can be used. Ceramic bone graft substitutes canbe used. In one embodiment, the implantable bone graft materialcomprises a composite of a ceramic and a polymer. The ceramic and thepolymer can be present at a weight ratio ranging from about 10:1 ceramicto polymer to about 2:1 ceramic to polymer. Alternatively, the weightratio of the ceramic to the polymer can range from about 2:1 (about 66%ceramic to about 33% polymer), from about 3:1 (about 75% ceramic toabout 25% polymer), from about 4:1 (about 80% ceramic to about 20%polymer), from about 9:1 (about 90% ceramic to about 10% polymer), fromabout 10:1 (about 99% ceramic to about 1% polymer). Other bone graftmaterials besides those specifically listed above can be used.

In some embodiments, any of the screws and instruments described above(such as the insertion tool) can be used with additional screws,implants, and instruments. In some embodiments, the implants andinstruments can be used with stabilization members, such as plates,screws, and rods.

STATEMENTS OF THE INVENTION

The following are non-limiting statements of the invention describingvarious aspects of the invention. Non-limiting reference is made belowto the enumerated elements in the drawings. However, these statements(and the claims to follow) are not limited to the embodiments depictedin the drawings.

Statement 1. An expandable screw 10 for orthopedic insertion andexpansion between a collapsed state and an expanded state, comprising:an upper externally-threaded body segment 12; a lowerexternally-threaded body segment 14 opposite the upper external threadsegments 12;

and an expansion member 16 extending along a longitudinal axis thereof,connecting the upper externally-threaded body segment 12 to the lowerexternally-threaded body segment 14, and configured during the expansionbetween the collapsed state and the expanded state to separate the upperexternally-threaded body segment 12 from the lower externally-threadedbody segment 14.

Statement 2. The screw of statement 1, wherein the expansion member 16expands the upper externally-threaded body segment 12 from the lowerexternally-threaded body segment 14 in a single expansion direction.

Statement 3. The screw of any one or more of the above statements,wherein the expansion member 16 expands the upper externally-threadedbody segment 12 from the lower externally-threaded body segment 14 in asingle expansion direction without a radial deflection of the upperexternally-threaded body segment 12 from the lower externally-threadedbody segment 14.

Statement 4. The screw of any one or more of the above statements,wherein the expansion member 16 expands the upper externally-threadedbody segment 12 from the lower externally-threaded body segment 14 whilethe upper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 remains in a fixed (or substantiallyfixed) orientation relative to each other.

Statement 5. The screw of any one or more of the above statements,wherein the upper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 comprise threads for securing thescrew to a bone segment of a patient.

Statement 6. The screw of any one or more of the above statements,wherein at least one of the upper externally-threaded body segment 12and the lower externally-threaded body segment 14 comprises an elongatedbody 22 having an aperture (which extend in longitudinal and traversedirections of the elongated body).

Statement 7. The screw of statement 6, wherein at least one of the upperexternally-threaded body segment 12 and the lower externally-threadedbody segment 14 comprise threads for securing the screw to a bonesegment in a patient, and the threads are disposed on outer peripheralsections of the upper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14.

Statement 8. The screw of statement 6, wherein at least one of the outerperipheral sections of one of the upper externally-threaded body segment12 and the lower externally-threaded body segment 14 comprises acylindrical shell.

Statement 9. The screw of any one or more of the above statements,wherein at least one of the upper externally-threaded body segment 12and the lower externally-threaded body segment 14 comprises an elongatedbody 22 having a cylindrical shape

Statement 10. The screw of statement 9, further comprising threadsdisposed on the elongated body for securing the screw to a bone segmentin a patient.

Statement 11. The screw of any one or more of the above statements,wherein the expansion member 16 comprises: a wedge member 18 connectingthe upper externally-threaded body segment 12 to the lowerexternally-threaded body segment 14; a nose member 20 having a distalend and a proximal end opposite the distal end, the nose member 20slidably connected to the upper externally-threaded body segment 12 andthe lower externally-threaded body segment 14; and an actuator 33disposed between the nose member 20 and the wedge member 18, fortranslation of the wedge member 18 along a longitudinal axis of thescrew.

Statement 12. The screw of statement 11, wherein the actuator 33 on afirst side slidably is connected the nose member 20 and on a second sideis connected to the wedge member 18; and translation of the wedge member18 relative to the upper externally-threaded body segment 12 and thelower externally-threaded body segment 14 (e.g., along the longitudinalaxis of the expandable screw) displaces the upper externally-threadedbody segment 12 and the lower externally-threaded body segment 14 awayfrom each other, thereby expanding the upper externally-threaded bodysegment 12 away from the lower externally-threaded body segment 14.

Statement 13. The screw of statements 11 or 12, wherein the expansionmember 16 further comprises: a pin coupling the actuator 33 to the nosemember 20.

Statement 14. The screw of statement 13, wherein the pin maintains aposition of the nose member 20 relative to the actuator 33 once theexpandable screw has been assembled.

Statement 15. The screw of any one or more of statements 11-14, whereinthe actuator 33 is threadably connected to the wedge member 18 such thatrotating the actuator 33 translates the wedge member 18 along thelongitudinal axis.

Statement 16. The screw of any one or more of statements 11-15, whereinthe wedge member 18 comprises a first wedge and a second wedge connectedtogether by a rail.

Statement 17. The screw of any one or more of statements 11-16, whereindovetail grooves on the wedge member 18 hold and slidably connect theupper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 to the wedge member 18.

Statement 18. The screw of any one or more of statements 11-17, whereindovetail grooves on the nose member 20 hold and slidably connect theupper externally-threaded body segment 12 and the lowerexternally-threaded body segment 14 to the nose member.

Statement 19. The screw of any one or more of statements 11-18, whereinthe dovetail grooves are disposed on a posterior side of the nosemember.

Statement 20. The screw of any one of statements 11-19, wherein aposterior of the actuator is configured to connect with an insertiontool for insertion of the implant between vertebra.

Statement 21. The screw of claim 1 any one of statements 11-21, whereinthe actuator is disposed closer to the nose member than to a posteriorend of the screw.

Statement 22. The screw of any one or more of statements 11-22, whereinthe actuator by turning advances the wedge member 18 toward the nosemember to expand the screw.

Statement 23. The screw of any one or more of statements 11-22, whereinthe actuator and the wedge member have respectively male and femalethreads to thereby advance the wedge member when the actuator is turned.

Statement 24. The screw of any one or more of statements 11-23, furthercomprising: a first set of dovetail grooves on the nose member which fixthe nose member to the upper externally-threaded body segment 12 and thelower externally-threaded body segment 14, and a second set of dovetailgrooves on the wedge member 18 which fix the upper externally-threadedbody segment 12 and the lower externally-threaded body segment 14 to thewedge member 18.

Statement 25. The screw of any one or more of statements 11-24, whereinthe wedge member 18 comprises a first wedge and a second wedge connectedtogether by a pair of rails, and a first through-hole in the firstwedge, a second through-hole in the second wedge, and a spacing betweenthe rails comprise a passageway for an insertion tool to connect to andturn the actuator.

Statement 26. The screw of any one or more of statements 11-26, whereinthe wedge member 18 comprises a first wedge and a second wedge connectedtogether by a pair of rails, and the second wedge at a posterior end hascounter torque slots by which an entirety of the screw is rotatable.

Statement 27. The screw of any one or more of statements 11-26, whereinthe nose member 20 slidably connects to the upper externally-threadedbody segment 12 and the lower externally-threaded body segment 14 by aset of dovetail groove on an external surface of the nose member.

Statement 28. The screw of any one or more of statements 11-27, whereinthe wedge member 18 comprises a first wedge and a second wedge, and aset of dovetail grooves on the first wedge and the second wedge slidablyconnect the wedge member to the upper externally-threaded body segment12.

Statement 29. The screw of any one or more of statements 11-28, whereinthe set of dovetail grooves on the first wedge and the second wedgeslidably connect the wedge member 18 to the lower externally-threadedbody segment 14.

Statement 30. The screw of any one or more of the above statements,wherein, upon expansion to the expanded state, windows for bone graftfilling exist a) between the upper externally-threaded body segment 12and the lower externally-threaded body segment 14 and b) in apertures 24forming elongated openings on both the upper externally-threaded bodysegment 12 and the lower externally-threaded body segment 14.

Statement 31. A system including the expandable screw of claim 1 whereinthe screw is for orthopedic insertion and expansion into a bone segmentof a patient, and the system comprising any one or more of the aboveexpandable screws in statements 1-30 and further comprising an insertiontool which is configured to connect to the expandable screw foractuation and expansion of the expandable screw.

Statement 32. A method for utilizing any one or more of the aboveexpandable screws in statements 1-30 for orthopedic insertion andexpansion of the expandable screw into a bone segment of a patient, themethod comprising:

-   -   inserting the expandable screw into the bone segment of the        patient; and expanding the expandable screw.

Numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described herein.

1. An expandable screw for orthopedic insertion and expansion between acollapsed state and an expanded state, comprising: an upperexternally-threaded body segment; a lower externally-threaded bodysegment opposite the upper external thread segments; and an expansionmember extending along a longitudinal axis thereof, connecting the upperexternally-threaded body segment to the lower externally-threaded bodysegment, and configured during the expansion between the collapsed stateand the expanded state to separate the upper externally-threaded bodysegment from the lower externally-threaded body segment, wherein theupper externally-threaded body segment and the lower externally-threadedbody segment comprise threads disposed on outer peripheral sections ofthe upper externally-threaded body segment and the lowerexternally-threaded body segment for securing the screw to a bonesegment of a patient.
 2. The screw of claim 1, wherein the expansionmember expands the upper externally-threaded body segment from the lowerexternally-threaded body segment in a single expansion direction.
 3. Thescrew of claim 1, wherein the expansion member expands the upperexternally-threaded body segment from the lower externally-threaded bodysegment in a single expansion direction without a radial deflection ofthe upper externally-threaded body segment from the lowerexternally-threaded body segment.
 4. The screw of claim 1, wherein theexpansion member expands the upper externally-threaded body segment fromthe lower externally-threaded body segment while the upperexternally-threaded body segment and the lower externally-threaded bodysegment remains in a fixed orientation relative to each other. 5.(canceled)
 6. The screw of claim 1, wherein at least one of the upperexternally-threaded body segment and the lower externally-threaded bodysegment comprises an elongated body having an aperture.
 7. (canceled) 8.The screw of claim 1, wherein at least one of the outer peripheralsections of one of the upper externally-threaded body segment and thelower externally-threaded body segment comprises a cylindrical shell. 9.The screw of claim 1, wherein at least one of the upperexternally-threaded body segment and the lower externally-threaded bodysegment comprises an elongated body having a cylindrical shape
 10. Thescrew of claim 9, further comprising threads disposed on the elongatedbody for securing the screw to a bone segment in a patient.
 11. Thescrew of claim 1, wherein the expansion member comprises: a wedge memberconnecting the upper externally-threaded body segment to the lowerexternally-threaded body segment; a nose member having a distal end anda proximal end opposite the distal end, the nose member slidablyconnected to the upper externally-threaded body segment and the lowerexternally-threaded body segment; and an actuator disposed between thenose member and the wedge member, for translation of the wedge memberalong a longitudinal axis of the screw.
 12. The screw of claim 11,wherein the actuator on a first side slidably is connected the nosemember and on a second side is connected to the wedge member; andtranslation of the wedge member relative to the upperexternally-threaded body segment and the lower externally-threaded bodysegment displaces the upper externally-threaded body segment and thelower externally-threaded body segment away from each other, therebyexpanding the upper externally-threaded body segment away from the lowerexternally-threaded body segment.
 13. The screw of claim 11, wherein theexpansion member further comprises: a pin coupling the actuator to thenose member.
 14. The screw of claim 13, wherein the pin maintains aposition of the nose member relative to the actuator once the expandablescrew has been assembled.
 15. The screw of claim 11, wherein theactuator is threadably connected to the wedge member such that rotatingthe actuator translates the wedge member 18 along the longitudinal axis.16. The screw of claim 11, wherein the wedge member comprises a firstwedge and a second wedge connected together by a rail.
 17. The screw ofclaim 11, wherein dovetail grooves on the wedge member hold and slidablyconnect the upper externally-threaded body segment and the lowerexternally-threaded body segment to the wedge member.
 18. The screw ofclaim 1, wherein, upon expansion to the expanded state, windows for bonegraft filling exist a) between the upper externally-threaded bodysegment and the lower externally-threaded body segment and b) inapertures forming elongated openings on both the upperexternally-threaded body segment and the lower externally-threaded bodysegment.
 19. A system including the expandable screw of claim 1 whereinthe screw is for orthopedic insertion and expansion into a bone segmentof a patient, and the system comprising the screw and further comprisingan insertion tool which is configured to connect to the expandable screwfor actuation and expansion of the expandable screw.
 20. A method forutilizing the expandable screw of claim 1 for orthopedic insertion andexpansion of the expandable screw into a bone segment of a patient, themethod comprising: inserting the expandable screw into the bone segmentof the patient; and expanding the expandable screw.